The present invention relates generally to charge pump circuits, and more particularly to low noise, high multiplication factor charge pump circuits.
“High multiplication factor” bias voltage generation in an integrated circuit is needed in many power-sensitive and cost-sensitive applications, including size-constrained systems for which large external components, such as inductors in various voltage boosting circuits, are prohibitive. Bias voltage generation circuitry for communication systems must be designed to meet stringent limitations on the generation and coupling of spurious RF noise levels into the RF components of the system. Also, high voltage multiplication or multiplier circuitry with very low spurious noise content within standard RF (radio frequency) communication frequency bands is needed to generate bias voltages and drive voltages for various applications, for example, to drive MEMS (microelectromechanical systems) actuators in an RF-MEMS varactor array product. It often is critical that such high-voltage multiplication circuitry meet very stringent limits on generation of spurious and/or load-sensitive noise generation and levels of noise energy within the standard RF communication bands.
Known high voltage multiplication charge pump circuits usually rely on a single high voltage pump in which the regulation of output voltage provided to a load is derived from a voltage generated by the single high voltage charge pump. If control of the voltage regulation is derived from the same charge pump that drives a variable load, there may be much greater load-dependent noise content and spurious noise content than is suitable for many RF applications. (The output ripple voltage, as further filtered and used for output regulation, is a primary influence in the generation of the spurious noise generated by a charge pump. Also, low power consumption is an important consideration in the design of integrated circuits for applications in the so-called “mobile product marker”.)
Thus, there is an unmet need for a low noise, high voltage multiplication charge pump circuit and method.
There also is an unmet need for a low noise, high-voltage-multiplication charge pump circuit and method which provide precise regulation of an output voltage supplied to a load and which generate very low levels of spurious RF noise and noise energy.
There also is an unmet need for a low noise, high-voltage-multiplication charge pump circuit and method which provide precise regulation of an output voltage supplied to a load and which generate very low levels of load-dependent noise.
There also is an unmet need for a low noise, high-voltage-multiplication charge pump circuit and method which provide precise regulation of an output voltage supplied to a load and which generate very low spurious RF noise levels and energy which does not rely on feedback from the output circuitry of that charge pump circuit to provide the precise regulation of the output voltage.
There also is an unmet need for a low noise, high-voltage-multiplication charge pump circuit and method which provide precise regulation of an output voltage supplied to a load, which generate very low levels of spurious RF noise and noise energy, and which consume relatively little power.